When I first started creating bra patterns for sale, I did them with the common ABC cup sizing. I am going to tell you… I did NOT like the ready-to-wear bra sizing at all. Why? Manufacturers often did not have standards that were consistent across all manufacturers or sometimes even within their own brand! The 34B size was usually the common denominator of all bras, but that’s not surprising. Almost all designers creating for the RTW market will create for a fit model sized 34B. It’s when they start to grade the pattern up that the problems occur. If grade rules are inconsistent or even off by 1/32″ or 1 mm, by the time you move up in size to the largest in the range, the sizes could be way off. So a G cup in one brand could be very different than a G cup in another
I was teaching a professional bra-makers course at the time for Mohawk College in Hamilton. I wanted to get away from that whole RTW sizing thing for my students so they wouldn’t have to buy dozens of bra patterns and still do trial and error while fitting. I wanted a system based on body measurements rather than the relative sizing that RTW used (the whole “sister” sizing thing). So I created my own system based on a 1/4″ increase in the distance from the wire line to the apex (known as the Bottom Cup Depth) for each successive size. I called that method the Universal Fit system, and it used 22 cups. Each of these cups could be fitted into a frame drafted from a wire size and multiple band lengths. If your cup was too small, you simply moved up one size in the cup. If you needed to swap out one frame for another, it could be done easily. My students loved it, but for the home sewer, it was still the ABC system.
Sadly, it wasn’t until 2010 that I decided to switch all my bra patterns to the BCD system once and for all. I am so glad I did! It makes bra fitting so much easier. However, there are women who use their old patterns but want to know what size they would be in the “new” BCD size. So here is my chart. If you want to know what BCD size you are, just find your “old” bra size in the chart and move left or right to the magenta column. That is your BCD size. Conversely, if you know your BCD size, move across the row to see what RTW sizes are equivalent.
There’s a lot to be learned from this chart. The BCD sizes are in the magenta columns on each side. The coloured cells indicate the “old” pattern colours. You had to buy 4 patterns in order to have all the pattern sizes. Now you buy one. The ready-to-wear sizes are in each cell, as well as the wire sizes. The bold line across the centre indicates which sizes use the “large” findings kits. The wire colours are at the top right. Rib Cage measurements are across the top in the Turquoise cells. The foam cup size equivalents are in the left column.
I hope this chart helps you with your bra-making adventure!
